The invention relates generally to gas turbines and, more particularly, to a gas turbine operable in a dual fuel mode where a liquid cartridge air blast circuit is passively fueled for gas operation.
Gas turbine engines typically include a compressor for compressing an incoming airflow. The airflow is mixed with fuel and ignited in a combustor for generating hot combustion gases. The combustion gases in turn flow to a turbine. The turbine extracts energy from the gases for driving a shaft. The shaft powers the compressor and generally another element such as an electrical generator.
In some designs, the combustors operate with backup fuel such as liquid fuel. A liquid fuel cartridge is inserted through a micromixing fuel nozzle assembly upstream of a combustion zone. When the turbine is not running with liquid fuel, air is purged through the liquid cartridges. A problem with the existing design, however, is that the air in the liquid cartridges contributes to NOx production in the combustion zone, which is undesirable.
It would be advantageous to address this problem by bleeding gas fuel into an annulus of the liquid cartridge to mix with air during gas only operation of the turbine.